Audio transducer



1m30, 1961sA H. RES 3,366,749

AUDIO TRANSDUCER Filed April 9, 1954 INVENTOR HUG /E B wfj fram/5yPatented Jan. 30, 1968 3,366,749 AUDIO TRANSDUCER Hugo Ries, LosAngeles, Calif., assignor of one-half to Alan A. Allen, Los Angeles, andone-half to Harry Z. Marx, La Jolla, Calif.

Filed Apr. 9, 1964, Ser. No. 358,475 Claims. (Cl. 179-1155) ABSTRACT OFTHE DISCLOSURE A sound-producing device having a post adapted to berigidly atlixed, by one end, to a sounding board, a voice coil mountedon said board, a permanent magnet assembly coaxial with the coil withone pole piece around and on the outside of the coil and a second polepiece within the coil, the post extending through a clearance hole inthe latter pole piece, and means resiliently mounting the magnet on thepost.

This invention relates to an audio transducer for producing sound in asounding board member on which the transducer is mounted.

An object of the present invention is to provide a transducer thatconverts the electrical impulses received from a sound head or similarsource into dynamic movement of a coil unit, the movement of the latterimparting conforming vibration to a post on which the transducer ismounted and which, in turn, is affixed to the sounding board member. Thelatter, thereby, produces sound translated from said electric impulses.

Another object of the invention is to provide a transducer in which themass of the magnetic components thereof has inertia that causes areactive vibratory movement in the post on which the same is mounted.

A further object of the invention is to provide an audio transducer, asabove characterized, provided with a resilient interconnection betweenthe post and magnetic components through which the vi-bratory drive ofthe post is effected.

This invention also has for its objects to provide such means that arepositive in operation, convenient in use, easily installed in a workingposition and easily disconnected therefrom, economical of manufacture,relatively simple, and of general superiority and serviceability.

The invention also comprises novel details of construction and novelcombinations and arrangements of parts, which will more fully appear inthe course of the following description, and which is based on theaccompanying drawing. However, said drawing merely shows, and thefollowing description merely describes, one embodiment of the presentinvention, which is given by way of illustration or example only.

In the drawing, like reference characters designate similar parts in theseveral views.

FIG. l is a top plan view, partly broken, of an audio transduceraccording to the present invention.

FIG. 2 is a cross-sectional View as taken on the line 2 2 of FIG. 1.

The audio transducer of the present invention is shown as mounted on asounding board member 5 which may be of any suitable material, as wood,plastic or metal, so long as the same is capable of sound-producingvibration.

The present transducer comprises, generally, a mounting post 6 that isaixed to the member 5, a coil unit 7 carried by the post 6, a permanentmagnet assembly 8, and oppositely arranged resilient means 9 mountingsaid assembly 8 on the post 6.

The post 6 is shown as an externally threaded rod 10 of a diametral sizeto be inexible. Said rod is preferably made of brass or othernon-magnetic material. A plate 11 is shown as threadedly connected toone end of said rod 10, suitable screws or other fastener elements `12connecting said plate to the sounding board 5. This arrangement of rod,plate and sounding board provides for said end of the rod being directedtoward the sounding board and enabling a tight and preferably recessedor indented engagement of the rod with the sounding board, merely byturning the rod so the threads thereof tighten in the plate 11. Theabove describes an exemplary manner of rigidly aiixing the post 6 to thesounding board 5.

The coil unit 7 is mounted on the rod 10 of the post 6, a nut 13threadedly engaged with the rod being provided for effectinglongitudinal adjustment of said unit on the rod. Said unit 7 is shown asa non-magnetic cup 14 that is staked to the nut 13 and has a cylindricalouter wall 15 concentric with the axis of said rod, and a voice coil 16wound on said wall 15. Said coil, in the usual manner, has conductorleads 17 that connect to a sound head or other such device. It will beunderstood that electro-magnetic impulses are brought to the coil bysaid leads 17.

The permanent magnet assembly is shown as a ring permanent magnet 18preferably of the ceramic-alloy type typically having opposite polarityat the outer and inner circumferential portions thereof. Such poles areindicated on magnet 18 in FIG. 2. Opposite ring-shaped, soft iron polepieces 19 and 20 are applied to the opposite side faces of the magnet18, thereby producing an assembly in which the magnet and pole piecesform a three-layer arrangement, clearly shown in FIG. 2. The innerperipheral surface 21 of the pole piece 19 is larger than the outerperipheral surface of the coil 16, providing a gap 'between saidsurfaces, as shown. The pole piece 20 is provided at its central partwith a projecting pole 22 that extends in-to the interior of the wall 15of the cup 14 with an annular gap between said pole 22 and said cupwall. The rod 10 extends through a clearance hole in the pole 22.

It will be seen that the coil 16 is disposed in the magnetic fieldbetween the pole piece 19 and the pole 22 and that the non-magnetic cup14 serves only as a carrier for the coil, having no magnetic elect onthe ield, as above described.

The resilient mounting means 9 is shown as a threearmed, non-magnetic,ilexible spider 23 staked at its center to the nut 13 and connected tothe pole piece 19 by screws 24 that fasten the ends of the spider arms25 to the outer portion of said pole piece, and a similar threearmed,non-magnetic, flexible spider 26 staked at its center to a nut 27 on therod 10 and connected to the pole piece 20 by screws 28 that fasten -theends of the spider arms 29 to the outer portion of said latter polepiece.

In the above manner, the magnet assembly is resiliently carried by thepost 6, the lat-ter vibrating, due to impulses of the voice coil,relative to the mass of the magnet assembly, the latter, by reaction,moving on its resilient connection 9 with the post 6.

The amount of the relative reaction movements of the magnet assembly 8and post 6 may be regulated by first mounting the magnet assembly on thepost 6 by means of the spider 23, and then, when applying the spider 26to said post and before applying the screws 28, setting said spider onthe post `6 relative to the spider 23, so as to inwardly flex therespective arms 25 and 29, as desired, and accordingly increasing ordecreasing the resilience of the magnet mount. The greater the flexureof the spiders, the higher the pitch of the sound produced in thesounding board 5. Such change in resilience of the spider arms may alsobe effected by locating the nut 27 in such spaced relation to the magnetassembly 8 that it will be necessary to lex the arms thereof toward thepole piece 20 before the screws can be applied. The spider arms 25 and29 will thus be exed oppositely outwardly from their inward flexure, asabove described.

Regardless how exed, the mounting spiders may be set to control pitch ofthe sound produced by the vibrating member 5.

While the foregoing has illustrated and described what is nowcontemplated to. be the best mode of carrying out the invention, theconstruction is, of course, subject to modification without departingfrom the spirit and scope of the invention. Therefore, it is not desiredto restrict the invention to the particular form of constructionillustrated and described, but to cover all modifications that may fallwithin the scope of the appended claims.

Having thus described the invention, what is claimed and desired to besecured by Letters Patent is:

1. An audio transducer comprising,

(a) a post adapted to be iixedly engaged by one end to a sounding board,

(b) an annular voice coil coaxially carried by said post and spacedradially therefrom,

(c) a permanent magnet assembly having one pole piece coaxial with saidvoice coil and spaced radially outwardly therefrom and a second polepiece radially spaced from and within said annular voice coil, and

(d) a rst resilient flexible mounting means on said post resilientlysupporting said one pole piece,

(e) a second resilient exible mounting means on said post spaced axiallyfrom said rst mounting means, resiliently supporting said Second polepiece,

(f) the second pole piece having an axial bore therethrough and the postextending freely through said bore and out of contact with the borewall, said post and magnet assembly having relative vibratory reactionmovements in response to electrical impulses in said coil.

2. An audio transducer according to claim 1 in which an annular space isprovided between the pole pieces, and a cup of non-magnetic materialmounts the coil on the post in said annular space with gaps separatingsaid coil from the pole pieces.

3. An audio transducer according to claim 1 in which each flexiblemounting means comprises a non-magnetic spider member with radialflexible arms.

4. An audio transducer according to claim 1 in which means areinterposed between the exible mounting means and the post and adjustablyengaged with the post to adjust the degree of flexure of the ilexiblemounting means.

5. An audio transducer comprising:

(a) an axial member adapted to be lixedly engaged at one end to asounding board,

(b) a voice coil concentrically carried by said member and radiallyspaced therefrom,

(c) a permanent magnet with one pole around and on the outside of thevoice coil and the other pole thereof within said coil, said magnetbetween its poles being disposed along the axis of said axial member andalong said axis at a position beyond the coil with respect to the pointof engagement of the axial member with the sounding board, and

(d) resilient means extending from said axial member and havingperipheral portions engaged with and mounting said magnet,

(e) the axial member and the magnet having relative reaction movementsin response to electrical impulses in the coil,

(f) said axial member sewing as the sole support for said magnet andvoice coil.

References Cited UNITED STATES PATENTS 2,341,275 2/1944 Holland 179-11552,756,281 7/ 1956 `Pittinger 179-1155 2,862,069 ll/l958 Marchand179-1155 3,125,647 3/1964 Rowy 179-1155 3,236,958 2/1966 Cohen 179-1155KATHLEEN H. CLAFFY, Primary Examiner.

A. A. MCGILL, Assistant Examiner.

